In the specification, olefins are referred to as:
"vinyl olefins" R--CH.dbd.CH.sub.2,
"vinylidene olefins" ##STR1## and internal olefins which are sub-divided as:
"di-substituted" R--CH.dbd.CH--R,
"tri-substituted" ##STR2## and "tetra-substituted" ##STR3## wherein R represents a hydrocarbon group. Internal olefins are also classified as ".beta.-internal" in which the double bond is connected to the .beta.-carbon atom as in: EQU R--CH.dbd.--CH.sub.3
and "deep internal" which is a di-substituted olefin in which the double bond is further towards the center of the olefin as in: EQU R'--CH.dbd.CH--R'
wherein R' is an aliphatic hydrocarbon group containing two or more carbon atoms.
The ".beta.-internal" olefins referred to herein are monomeric. This means they contain the same number of carbon atoms as the initial vinyl-olefins but the olefinic double bond has moved toward the center of the molecule.
The "deep internal" olefins referred to herein are dimers of the initial vinyl olefins. For example, a deep internal dimer of 1-octene contains 16 carbon atoms. They differ from vinylidene dimers in that their olefinic double bond is in the linear chain near the center of the molecule.
Vinyl-olefins can be dimerized to form deep internal olefin dimers using a catalyst such as a Friedel Craft catalyst (e.g. BF.sub.3) The present invention is not concerned with such Friedel Craft catalyzed dimerizations.
Vinyl-olefins can also be dimerized to form vinylidene olefins as described in Ziegler U.S. Pat. No. 2,695,327. Aluminum alkyl dimerization also forms a much smaller amount of a non-vinylidene dimer referred to herein as "deep internal dimers."
Vinylidene olefins are very useful. For example they may be further dimerized using a Friedel Crafts catalyst to form a valuable synthetic lubricant as described in Shubkin U.S. Pat. No. 4,172,855.